1. Field of the Invention
This invention relates to medical heating devices comprising a probe that causes heating of target tissue for tissue ablation, tissue cutting, or tissue shrinking, and, in particular, to the heating and temperature control of such devices and their probes. The probe cauterizes tissue as it ablates, cuts, or shrinks. Cauterization is the process of destroying tissue using heat conduction from a metal probe heated by electric current where the heating stops bleeding from blood vessels in soft tissue. The invention may be used in medical, dental, and veterinary procedures involving soft tissue ablation, cutting, or shrinking.
2. Description of Related Art
Medical heating devices are presently used for selected tissue ablation in a number of treatment regimens. Typically, the heat is generated using radiofrequency-induced arcing between two points or by electric current conduction through the body to a grounding device. Examples include those describe in U.S. Pat. Nos. 6,132,426 and 6,969,644. One problem with electric-arc-based heating devices is the danger of electrical fires that can occur in a medical practice, operating suite, or hospital. Current conduction devices lack sufficient control over the path the current takes through the tissue from source to ground. The amount of tissue heating that occurs is also difficult to control, potentially leading to unnecessary injury as a side effect to the treatment.
Other prior art medical heating devices use standard electrical heating elements that are thermostatically controlled with switches or thermocouples. These devices control heat production and probe temperature essentially by switching the electrical heating element fully on or fully off, resulting in a temperature fluctuation of the ablation or cutting probe of the medical device that is more than optimal for tissue ablation or tissue cutting purposes.
A self-limiting medical heating device that offers much better control over the location and amount of tissue heating, as well having safety improvements to both the patient and operator is highly desirable.